I am about to let my players face Adimarchus. The are already on Carceri and will learn the location of Skullrot tonight. After a (possible) detour to the rock (Byakala), they will enter the asylum in about two weeks. Any last minute recommendations, someone wants to give ?

Reason is: I've never played high-level PCs, let alone high-level bad-boys and I feel, they may end up having a way too easy time defeating a demon prince, if I'm not prepared.

They've been showing pretty good tactics, Extended Hero's feast every other day is standard. Death ward by Nidrama on everyone as well. Together with a circle of protection evil, they are pretty much immune to all the really dangerous attacks by the run-of-the-mill antagonist.

For example, they didn't flinch much, when Orbius made a second appearance in his highly inflated form, let alone lose a member.

So, how do I best put them to a real test. I'd like to challenge their strategy, but I fear that even the very good armor class and SR of our prince won't be more than a speed bump to them, if I can't somehow slow their team tactics down.

I've not actually run this particular encounter, although I'm chomping at the bit to do so. But I can speak from my experiences running other high-level battles in 2nd and 3rd edition. I guess I have two things to say.

#1 You've answered your own question, here:

nib wrote:

if I can't somehow slow their team tactics down.

if your group are working like a team, then well done to them - they should be rewarded for doing so. But also, they shouldn't fall back on the same routines and get complacent. You know what they usually do, and if it doesn't smack too much of meta-gaming, then disrupt their regular formation and tactics. It'll be a wake up call and make the whole thing more of a challenge.

#2 Know what the bad guys can do. Simple preparation is the key, here. Read and reread Adi's stat block. Know both his forms inside and out.

Final thought - if you're worried about them finding it too easy, then don't be afraid to beef up the final encounter. More HP for the bad guy is the easiest way, having them summon help and giving them extra dispels are the other common "easy boosts" to apply to the BBEGs.

Many thanks for the suggestions, I must have overlooked (or disgregarded immediately) the devastating Blasphemy and Word of Chaos abilities. With those alone, he would be able to destroy the party in 2 rounds, except the Smoking Eye character, who is actually chaotic good (and evil). The rest: LN, CG, NG, CN, NG, LN.

Although that would actually be exactly what Adimarchus is supposed to do, when running him by the book, I still don't see how this can be the intended outcome, as it would be pretty much inevitable from the start. Actually, I'm not going to do that, as it would end the game right there with a bad taste to boot.

The question I'm posing myself is now, whether I should decrease the caster level of the abilities and still scare the hell out of them by paralyzing half the party, maybe even to start a chat with the remaining Smoking Eye, whether I should just keep those abilities for a last ditch resort, if the battle goes too well for the party, or whether I should I just drop them for the sake of survivability.

What will offer the best value for money and still be in flavor ?

I also wonder, whether Death Ward protects from being killed anyway ?

Many thanks,
Nib

[edit]
PS: What do you think about killing them off ruthlessly and then adding a mini-adventure starring Nerull (as god of death) who is pissed off that Embril in the end succeeded in freeing Adimarchus anyway, and hence returns the party to live with the task to finish Adimarchus off. This would also circumvent the problem, that, in principle, the party needs to fight A. twice, once on Carceri, and then again on his home plane...

I'd look at your groups save bonuses and weigh that against their ability to bring back fallen members. A Revivify or two could bring them back into the fight and cause a delay in their teamwork. If nothing else it would be an excellent story. And remember that they have to kill both halves. If they're unlucky and Addy never switches forms, they're going to finish the one only to have to fight the fully fresh second. You might even play it that way on purpose. It sounds like your group is one that doesn't need to be handled with kid gloves. Bring the hammer down. :)

Edit: No, Death Ward will not, as both abilities are Evocations. >:) I do agree with the paralyze them and have a chat with the Smoking Eye character. However, if they have debuff removal, that may not play out as well as you like.

Hell, combine the two SLAs into one Sit-Down-Non-Chaotic-Evil ability and THEN have a talk with the heritor character. Have Addy alternate between suggesting a father-son-rule-the-galaxy idea and trying to rip the characters face off as he switches forms. Make a tense few rounds of one-on-one before the others get to do anything. Depends on how the other six players will feel being forced out of the action. Maybe give them the ability to speak while paralyzed.

Edit Edit: I love discussing these things on the forum. Gives me new ideas for my next running. X3

Many thanks for the suggestions, I must have overlooked (or disgregarded immediately) the devastating Blasphemy and Word of Chaos abilities. With those alone, he would be able to destroy the party in 2 rounds, except the Smoking Eye character, who is actually chaotic good (and evil). The rest: LN, CG, NG, CN, NG, LN.

Although that would actually be exactly what Adimarchus is supposed to do, when running him by the book, I still don't see how this can be the intended outcome, as it would be pretty much inevitable from the start. Actually, I'm not going to do that, as it would end the game right there with a bad taste to boot.

The question I'm posing myself is now, whether I should decrease the caster level of the abilities and still scare the hell out of them by paralyzing half the party, maybe even to start a chat with the remaining Smoking Eye, whether I should just keep those abilities for a last ditch resort, if the battle goes too well for the party, or whether I should I just drop them for the sake of survivability.

What will offer the best value for money and still be in flavor ?

I also wonder, whether Death Ward protects from being killed anyway ?

Many thanks,
Nib

My group (average level 20) happens to be in the final fight against Adimarchus (we use 3.5 core rules only). The CL30 is a mistake in the magazine, which unfortunately was not corrected in the hard-cover. If you search the database you will find James' reply [url=http://paizo.com/dungeon/messageboards/shackledCity/archives/quickAdventurePathErattaSpoiler[/url] on this matter. It should be CL20, similar to other demon-lords like Graz'zt. And what would be the point in killing the party outright?

On the other hand, deathward (Nidrama can cast that spell, which she did in on all group members) might protect the characters from instant death depending on your own ruling. As far as I understand it this spell protects against all death effects and not only those with the death descriptor (immune to all death spells, magical death effects, etc.). That leaves only the paralyzation :-).
Anyhow, after 8 rounds the party has done 470 hp of damage against his angelic form and 270 against the demon form. Currently the monk with the smoking eye is at -7hp, the wizard without functional spells, the rogue searching for his cold iron arrows that missed and Nidrama paralyzed. Everything depends now on the priest (one miracle left) and the fighter (hurt but not dead yet).

Our DM played this well using the CR30 Blaspheme. He used it to kill off the entire party except the Smoking Eye character (myself actually). Then through another plot device he gave me the opportunity to make use of a wish spell to "turn back one recent event". In essence, he left he party's fate up to me.